CA Dept. of Public Health UC Davis Arbovirus Research and Training Mosquito and Vector Control Assoc. of CA

Case Counts by County

CountyDead birds
Alameda16
Alpine-
Amador-
Butte3
Calaveras-
Colusa-
Contra Costa11
Del Norte-
El Dorado2
Fresno-
Glenn-
Humboldt1
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles9
Madera-
Marin-
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange5
Placer40
Plumas-
Riverside5
Sacramento232
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin11
San Luis Obispo-
San Mateo5
Santa Barbara-
Santa Clara43
Santa Cruz2
Shasta4
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus1
Sutter4
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo36
Yuba-
Total430

WNV Activity by County
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2018 | 2017 | 2016 | 2015 | 2014
2013 | 2012 | 2011
2010 | 2009 | 2008
2007

Press Releases

CDPH REPORTS FIRST CONFIRMED HUMAN WEST NILE VIRUS FATALITIES OF 2009

Sep 17, 2009

SACRAMENTO - A Fresno County man and a Merced County man are the first reported West Nile virus (WNV) fatalities in California this year, reported Dr. Gilberto Chavez, acting chief deputy director of the California Department of Public Health (CDPH).

"These fatalities underscore the importance of taking precautions to protect from mosquito bites," Chavez said. "Californians should use insect repellent and eliminate all sources of standing water that can sustain mosquito breeding."

WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds. Despite these two fatalities, the number of reported WNV illnesses in California this year is lower than last year. In September 2008, there were 193 human cases. To date this year, 36 people in 10 California counties have been diagnosed with WNV.

"We generally expect the level of WNV activity to cycle from year to year and from region to region, but probably the greatest reason for the decreased activity in 2009 is the relatively cool summer compared to previous years," Chavez explained. "We can also credit better mosquito control efforts."

Most infected individuals will not experience any illness. Individuals 50 and older have a higher chance of getting sick and are more likely to develop serious symptoms when infected with WNV. People who have diabetes and/or hypertension are at greatest risk for serious illness.

Chavez said that the most effective ways for individuals to prevent exposure to mosquito bites and WNV are to remember the "Four D's":


  1. DEET - ApplyinspectrepellentcontainingDEET,picaradin,oiloflemon eucalyptus or IR 3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.

  2. DRESS - Wear clothing that reduces the risk of skin exposure.

  3. DAWN AND DUSK?Mosquitoes that carry WNV bite the early morning and evening so it is important to wear repellent at this time. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

  4. DRAIN - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. If you have a pond, use mosquito fish (available from your local mosquito and vector control agency) or commercially available products to eliminate mosquito larvae.


WestNile.ca.gov includes the latest information on WNV activity in the state. Report all dead birds and dead tree squirrels on the Web site or by calling toll-free 1-877-WNV- BIRD (968-2473).

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Compared to previous year and previous five-year average to date

As of Sep 14, 2018201820175Y AVG
Counties373939
Human cases79143188
Dead birds4303371087
Mosquito samples173029792773
Sentinel chickens112204277
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2018 YTD activity -

WNV Reports

Weekly Report

09.14 Arbovirus Bulletin #24
09.14 2018 YTD SLEV Activity Map
09.14 2018 YTD WNV Activity Map

Humans

09.10 2018 Human WNV Incidence Report
09.05 2003-2018 WNV Case Summary
03.29 2017 Human WNV Incidence Report

Dead Birds

09.14Reported, Tested, Positive 2018
09.14Positive Species for 2018
09.14Positive Counts by City/County for 2018

Mosquitoes

09.14 AMOR - EVS Week 36
09.14 AMOR - GRAVID Week 36
09.14 AMOR - NJLT Week 36
- view report archives -